JPH1069104A - Electrophotographic photoreceptor and electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the production of a ghost image, a residual potential and a dark decay by incorporating a specified triarylamine compd. into a charge producing layer. SOLUTION: The charge producing layer contains a triarylamine compd. expressed by formula. In formula, Ar1 , Ar2 are phenyl groups which may have substituents of alkyl groups, phenyl groups, alkoxy groups or alkyl-substd. phenyl groups, or polycyclic aromatic groups which may have alkyl substituents, or aromatic heterocyclic groups. The amt. of the triarylamine compd. is about 1 to 30wt.%, and preferably 1 to 10wt.%. The charge producing layer is formed preferably to <=2μm thickness, and more preferably 0.01 to 1μm thickness. In this case, lots of particles of the charge transfer agent are present on the interface between the charge producing layer and the charge transfer layer and around each particle of charge producing agent so that the carrier generated is instantly injected into the charge transfer agent and moved to the charge transfer layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a function-separated type electrophotographic photoreceptor which is less affected by carrier traps, greatly improves ghost generation, and is excellent in residual potential, dark decay, and the like.
And an electrophotographic apparatus using the electrophotographic photosensitive member.

[0002]

2. Description of the Related Art In recent years, as an electrophotographic photosensitive member used for a copying machine, a laser printer, an LED printer, and the like using an electrophotographic method, an organic photosensitive material has been mainly used. Representative charge generators include, for example, phthalocyanine pigments and disazo pigments. Regarding the charge transporting agent, for example,
Nos. 59483, 57-195254, JP-A-2-178668, JP-A-2-190862, JP-A-3-101737, and JP-A-3-127765 disclose synthesis of triarylamine compounds. A method and an application to an electrophotographic photoreceptor are disclosed, and JP-A-62-247374 discloses a benzidine compound. These are often used as constituents of a layered type function-separated type electrophotographic photosensitive member. However, the conventional function-separated type electrophotographic photoreceptor has a drawback that ghosts, which are considered to be caused by carrier traps, occur in repeated use at the initial stage.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the conventional function-separated type electrophotographic photosensitive member and achieve the following objects. The present invention relates to a function-separated type electrophotographic photoreceptor which is less affected by carrier traps, significantly improves ghosting, is excellent in residual potential, dark decay, and the like, and an electrophotographic apparatus using the electrophotographic photoreceptor. The purpose is to provide.

[0004]

Means for Solving the Problems As a result of intensive studies by the inventors of the present invention in order to improve the occurrence of ghost which is a drawback of the function-separated type electrophotographic photosensitive member, It has been found that the generation of ghosts can be greatly improved if a specific charge transport agent is mixed in advance in the charge generation layer.

[0005] The present invention has been made based on the above findings by the inventors, and the means for solving the above problems are as follows. That is, first, in an electrophotographic photoreceptor obtained by laminating at least a charge generation layer and a charge transport layer on a conductive support, the charge generation layer is a triarylamine-based compound represented by the following general formula (I). An electrophotographic photoreceptor comprising a compound. General formula (I)

[0006]

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(However, in the general formula (I), Ar ₁ and A
r ₂ is an alkyl group, a phenyl group, a phenyl group optionally substituted with an alkoxy group or an alkyl-substituted phenyl group, a polycyclic aromatic group optionally substituted with an alkyl group, or an aromatic heterocyclic group; Represents a ring group. In the electrophotographic photoreceptor, it is preferable that the charge generation layer contains a phthalocyanine compound represented by the following general formula (II) as a charge generation substance. General formula (II)

[0008]

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(However, in the general formula (II), M represents Cu, Fe, Mg, Si, Ge, S
It represents a form containing n, Pb, In, Ga, Al, and Ti, or a form in which two hydrogen atoms are added. X represents a hydrogen atom, an alkyl group, an alkoxy group, an alkoxyalkyl group, a nitro group, a cyano group, or a halogen atom. m is 0 to 4
Represents an integer. A second aspect is an electrophotographic apparatus of a contact charging system, comprising the electrophotographic photoreceptor according to claim 1 or 2. A third aspect is an electrophotographic apparatus of a reversal development system, comprising the electrophotographic photosensitive member according to claim 1 or 2.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The above-mentioned ghost is a development in which a dark potential portion, which is often used in copying machines, laser printers, LED printers and the like, is a non-developing portion and a bright potential portion is a developing portion. In the process (reversal development method), if the sensitivity (image area) where light was applied during the previous printing decreases, and a halftone image is taken during the next printing,
This refers to a phenomenon in which an image portion at the time of previous printing appears as an afterimage.

When light is applied to the charge generating agent in the charge generating layer to generate carriers, the carriers move inside and between the particles of the charge generating agent, and are finally carried to the charge transporting layer. However, in general, the interface between the charge generation layer and the charge transport layer becomes a barrier (barrier) for carrier transport, and easily becomes a trap site for carriers. For this reason, space charges easily accumulate at the interface between the charge generation layer and the charge transport layer. When space charges (holes in the negatively charged developing method) are trapped in the image (exposure) portion at the time of the previous print, the space electric field in the charge generation layer is affected by the trap carriers at the time of charging the next print. Has been reduced. For this reason, the potential does not drop sufficiently in the halftone image of the next print, and an afterimage appears as a ghost.

However, in the electrophotographic photoreceptor of the present invention,
Since the charge transport layer is premixed with the charge transport agent, a large number of charge transport agents are present at the interface between the charge generation layer and the charge transport layer and around the individual charge generators. It is quickly injected into the transport agent and moves to the charge transport layer. Even if trap sites are present at the interface, the movement of carriers to the charge transport layer is less likely to be affected by passing through the charge transport agent, and the carriers are not deposited on the image (exposed) portion of the previous print. In the present invention, the effects as described above are considered,
As a result, the occurrence of ghost is greatly improved.

Hereinafter, the electrophotographic photosensitive member and the electrophotographic apparatus of the present invention will be described in detail with reference to the drawings. (Electrophotographic Photoreceptor) FIGS. 1 and 2 are schematic explanatory sectional views showing one example of the electrophotographic photoreceptor of the present invention. The electrophotographic photoreceptor shown in FIG. 1 has a charge generation layer 2 and a charge transport layer 3 laminated on a conductive support 1 in this order. The electrophotographic photoreceptor shown in FIG. 2 has a charge transport layer 3 and a charge generation layer 2 laminated on a conductive support 1 in this order.

-Conductive Support-The conductive support is not particularly limited, and examples thereof include known supports for an electrophotographic photosensitive member. Specific examples of the conductive support include films of metals such as aluminum, nickel, chromium, and stainless steel; aluminum, titanium, nickel, chromium, stainless steel, gold, vanadium, tin oxide, indium oxide, and ITO.
And the like; a plastic film or the like provided with a thin film such as a paper; a paper or a plastic film coated or impregnated with a conductivity imparting agent; These conductive supports are used in an appropriate shape such as a drum shape, a sheet shape, and a plate shape, but are not limited thereto. The conductive support may be appropriately subjected to a roughening treatment or the like according to the purpose. On the conductive support,
If necessary, a subbing layer known per se may be provided. The thickness of the undercoat layer is usually 0.01 to 10
μm, and preferably 0.05 to 2 μm.

-Charge transport layer-The charge transport layer is not particularly limited, and examples thereof include known charge transport layers of an electrophotographic photosensitive member. The charge transport layer generally includes at least a charge transport agent and a binder resin. Suitable examples of the charge transport agent include a triarylamine compound represented by the general formula (I) and a benzidine-based compound represented by the following general formula (III). These may be used alone or in combination of two or more.

General formula (III)

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(However, in the general formula (III), R ₁ and R ₁ ^′
May be the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group or an alkoxy group. R ₂ , R ₂ ^′ , R ₃ and R ₃ ^′ may be the same or different and each represents an alkyl group, an alkoxy group or a substituted amino group. m and n each represent 1 or 2. )

Specific examples of the triarylamine compound represented by the general formula (I) are shown in Tables 1 to 4 below.

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

[Table 3]

[0022]

[Table 4]

Among these triarylamine compounds, those used in the examples described below are preferable in terms of easy availability, easy handling, and the like.

There is no particular limitation on the binder resin.
Known as a binder resin of the charge transport layer, for example,
Polycarbonate resin and the like can be mentioned. Among the polycarbonate resins, a polycarbonate resin containing one or both of monomer units represented by the following general formulas (IV) and (V) is preferable.

Formula (IV)

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General formula (V)

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Specific examples of such a polycarbonate resin include poly (4,4'-isopropylidene-diphenylene carbonate) and poly (4,4'-cyclohexylidene-diphenylene carbonate). In the present invention, as the binder resin, the following film-forming resins can be used together with the polycarbonate resin. As the film-forming resin,
Examples include polyarylate, polyester, polystyrene, styrene-acrylonitrile copolymer, polysulfone, polymethacrylate, styrene-methacrylate copolymer, and other vinyl polymers. The binder may be appropriately synthesized or commercially available.

The content of the charge transporting agent in the charge transporting layer is preferably from 10 to 75% by weight,
~ 60% by weight is more preferred. If the content is less than 10% by weight, the sensitivity of the electrophotographic photoreceptor may decrease. If the content exceeds 75% by weight, the mechanical strength of the charge transport layer may decrease. The thickness of the charge transport layer is preferably from 2 to 100 μm, more preferably from 10 to 30 μm.

The charge transport layer is formed by dissolving the charge transport agent and the binder resin in an appropriate solvent to form a solution. The solution is coated on the conductive support or the like according to a known method, and dried. It can be formed by performing. Examples of the solvent include organic solvents known per se, for example, aromatic hydrocarbons such as benzene, toluene, xylene, mesitylene, and chlorobenzene, acetone,
Ketones such as butanone, methylene chloride, chloroform, halogenated aliphatic hydrocarbons such as ethylene chloride, tetrahydrofuran, dioxane, ethylene glycol, cyclic or linear ethers such as diethyl ether, and the like, or a mixture thereof A mixed solvent and the like can be mentioned. To the charge transport layer, additives known per se, such as an antioxidant, may be appropriately added in a range that does not impair the function as the charge transport layer, depending on the use, purpose, and the like of the electrophotographic photoreceptor. Can be.

-Charge Generating Layer- The charge generating layer generally contains at least a charge generating agent and a binder resin. In the present invention, the triarylamine compound represented by the general formula (I) is further used. Comprising. The general formula (I) in the charge generation layer
Is 1 to 30% by weight, preferably 1 to 10% by weight. If the content is less than 1% by weight, desired characteristics may not be obtained. If the content is more than 30% by weight, the charge generation function of the charge generating agent is adversely affected,
In some cases, the sensitivity of the electrophotographic photoreceptor is reduced, or the mechanical strength of the charge generation layer is significantly reduced, and delamination may occur. The charge transporting agent contained in the charge generating layer is preferably the same as the charge transporting agent contained in the charge transporting layer. However, as long as the charge transporting agent is a triarylamine compound represented by the general formula (I), the specific structure of the triarylamine compound is included in the charge transporting layer and the specific structure is included in the charge generating layer. However, even if they differ between them, there is no significant effect on the characteristics of the electrophotographic photosensitive member.

The charge generator is not particularly limited as long as it can be mixed with the triarylamine compound represented by the general formula (I), and may be appropriately selected from charge generators known per se. it can. Among the charge generating agents, those in the form of particles are preferred from the viewpoint of simplicity in the production method. Specific examples of the charge generating agent include various organic charge generating substances such as a phthalocyanine compound, a polycyclic condensed compound, and a disazo compound. In the present invention, among these, among the above, the general formula (II) The phthalocyanine compounds shown are preferred. The general formula (II)
Examples of the phthalocyanine compound represented by include those known per se, specifically, chlorogallium phthalocyanine, hydroxylgallium phthalocyanine,
Preferable examples include oxotitanyl phthalocyanine, dichlorotin phthalocyanine, and metal-free phthalocyanine. The compounding ratio (weight ratio) of the charge generating agent and the binder resin contained in the charge generating layer is preferably from 40: 1 to 1:20, more preferably from 10: 1 to 1:10.

As the binder resin, a film-forming polymer which is hydrophobic, has a high dielectric constant, and is electrically insulating is preferably used. The electrically insulating film-forming polymer is not particularly limited, but includes, for example, polycarbonate, polyester, methacrylic resin, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl acetate, styrene-butadiene copolymer, and chloride. Vinylidene-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N -Vinyl carbazole and the like. These may be used alone or in combination of two or more.

The charge generating layer is formed by dissolving the charge transporting agent, the charge generating agent and the binder resin in the solvent to form a solution, and applying the solution on the conductive support or the like according to a known method. It can be formed by coating and drying. The thickness of the charge generation layer is preferably 2 μm or less, more preferably 0.01 to 1 μm. If the thickness exceeds 2 μm, free carriers frequently occur in the charge generation layer, which may cause image defects such as fog. In addition, additives known per se can be appropriately added to the charge generation layer within a range that does not impair the function as the charge generation layer, depending on the use and purpose of the electrophotographic photoreceptor.

In the electrophotographic photoreceptor of the present invention, an intermediate layer or the like known per se may be provided between the charge transport layer and the charge generation layer according to the purpose.

(Electrophotographic Apparatus) The electrophotographic apparatus of the present invention uses the electrophotographic photoreceptor of the present invention as an electrophotographic photoreceptor in a copier, a printer, a facsimile apparatus and the like known per se. In the electrophotographic apparatus of the present invention, as long as the electrophotographic photoreceptor of the present invention is used, other parts are not particularly limited, and may be known. The charging method of the electrophotographic apparatus is not particularly limited, but a contact charging method and a reversal developing method are preferable.

In the present invention, the contact charging system is
For example, a conductive elastic roller, a film-charged conductive brush, conductive magnetic particles,
This means a method of directly charging the surface of the electrophotographic photosensitive member with an applied voltage of up to 2 kV. Specifically, as shown in the schematic explanatory view of FIG. 3, an electron having a surface layer 10 of a charging roll 9, a charge generation layer 7 and a charge transport layer 8 on a conductive support 6 in this order. The surface of the electrophotographic photoreceptor 5 is brought into contact with the surface of the electrophotographic photoreceptor 5 and a voltage is applied from the charging roll 9 side, whereby the surface of the electrophotographic photoreceptor 5 is directly charged and then developed.

In the present invention, the reversal developing method is
This means a method in which toner is adhered to a portion where the surface potential is reduced by light irradiation and development is performed. Specifically, as shown in the conceptual diagram of FIG. 4, a potential substantially equal to the surface potential is applied to the developing electrode to reverse the potential difference between the dark part and the bright part, and to the same polarity as the polarity of the formed surface potential. This is a negative-positive developing method using a charged toner, in which a portion having a reduced surface potential is formed as shown in FIG. 4A, and the toner is attached to the portion as shown in FIG. 4B. This means a method of performing development.

[0038]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1 An aluminum tube cold-drawn after extrusion of φ30 × 253 mm was prepared, roughened by liquid honing, and then subjected to aqueous cleaning. This was used as a conductive support. Next, as an undercoat layer, 20 parts by weight of acetylacetone zirconium butoxide (Orgatics ZC540, manufactured by Matsumoto Kosho), 2 parts by weight of γ-aminopropyltriethoxysilane (A1100, manufactured by Nippon Yunika), polyvinyl butyral resin 1 A solution consisting of 0.5 parts by weight (Eslec BM-S Sekisui Chemical Co., Ltd.) and 70 parts by weight of n-butyl alcohol was dip-coated on the aluminum tube, and then dried at 135 ° C. for 15 minutes. The thickness is 1.
An undercoat layer of 0 μm was formed on the conductive support. Next, as a charge generation layer, 10 parts by weight of chlorogallium phthalocyanine, 10 parts by weight of a vinyl chloride-vinyl acetate copolymer (VMCH, manufactured by Union Carbide Co.), and n-acetic acid
After stirring 200 parts by weight of -butyl in a sand mill using 1 mmφ glass beads for 3 hours, 1 part by weight of a charge transporting agent of the following structural formula (1) was added to this dispersion, and the mixture was stirred again for 1 hour. The resulting dispersion was dip-coated on the undercoat layer to form a charge generation layer having a thickness of 0.2 μm.

[0040]

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Next, 1 part by weight of the charge transporting agent of the structural formula (1) and 1 part by weight of the polycarbonate Z containing a monomer unit represented by the structural formula (2) as a binder resin were mixed with monochlorobenzene 6 A 25 μm-thick charge transport layer was formed by dip coating the solution dissolved in parts by weight on the charge generation layer. Thus, a function-separated type electrophotographic photosensitive member having three layers was produced.

[0042]

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Example 2 In Example 1, a charge transporting agent represented by the following structural formula (3) was used instead of the charge transporting agent represented by the structural formula (1) as a charge transporting agent to be added to the charge generation layer. An electrophotographic photosensitive member was prepared in the same manner as in Example 1, except that 1 part by weight of the agent was added.

[0044]

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Example 3 In Example 1, a charge transporting agent represented by the following structural formula (4) was used instead of the charge transporting agent represented by the structural formula (1) as a charge transporting agent to be added to the charge generation layer. An electrophotographic photosensitive member was prepared in the same manner as in Example 1, except that 1 part by weight of the agent was added.

[0046]

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Example 4 In Example 1, a charge transporting agent represented by the following structural formula (5) was used instead of the charge transporting agent represented by the structural formula (1) as a charge transporting agent to be added to the charge generating layer. An electrophotographic photosensitive member was prepared in the same manner as in Example 1, except that 1 part by weight of the agent was added.

[0048]

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(Example 5) In Example 1, a charge transporting agent represented by the following structural formula (6) was used instead of the charge transporting agent represented by the structural formula (1) as a charge transporting agent to be added to the charge generating layer. An electrophotographic photosensitive member was prepared in the same manner as in Example 1, except that 1 part by weight of the agent was added.

[0050]

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Comparative Example 1 An electrophotographic photosensitive member was prepared in the same manner as in Example 1, except that no charge transporting agent was added to the charge generating layer.

(Comparative Example 2) In Example 1, a charge transporting agent represented by the following structural formula (7) was used instead of the charge transporting agent represented by the structural formula (1) as a charge transporting agent to be added to the charge generating layer. An electrophotographic photosensitive member was prepared in the same manner as in Example 1 except that 2 parts by weight of the agent was added.

[0053]

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<Evaluation> Each of the electrophotographic photosensitive members obtained as described above was subjected to a laser printer (manufactured by Apple Inc.).
laser writer select 360 / contact charging, erase-less reversal developing type electrophotographic apparatus), and the ghost grade of the copied image was visually evaluated according to the following criteria. The ghost grade is performed using two print samples, and the first print sample and the second print sample are _Go ,
The evaluation was made in five stages of G ₁ , G ₂ , G ₃ and G ₄ . _Go is
Means a state in which there is no occurrence of a ghost, as directed to the G _4,
This means a state in which ghosts are sequentially observed. In addition,
G ₁ The following grades are no practical problem. At the same time, the initial residual potential and dark decay were evaluated using a laser printer modified scanner (XP-11: manufactured by Fuji Xerox Co., Ltd.). The results are shown in Tables 5 and 6.

[0055]

[Table 5]

[0056]

[Table 6]

[0057]

According to the present invention, the above-mentioned disadvantages of the conventional function-separated type electrophotographic photosensitive member can be solved. Further, according to the present invention, the effect of the carrier trap is small, the occurrence of ghost is greatly improved, the residual potential, the function-separated electrophotographic photosensitive member excellent in dark decay, etc.,
Also, by using the electrophotographic photoreceptor, an electrophotographic apparatus having excellent practical performance can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view illustrating an example of an electrophotographic photosensitive member of the present invention.

FIG. 2 is a schematic sectional view showing another example of the electrophotographic photosensitive member of the present invention.

FIG. 3 is a schematic explanatory view showing an example of a contact charging system.

FIG. 4 is a conceptual diagram illustrating an example of a reversal developing method.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 conductive support 2 charge generation layer 3 charge transport layer 5 electrophotographic photoreceptor 6 conductive support 7 charge generation layer 8 charge transport layer 9 charging roll 10 surface layer

Claims (4)

[Claims] 1. An electrophotographic photoreceptor comprising at least a charge generation layer and a charge transport layer laminated on a conductive support, wherein the charge generation layer comprises an arylamine-based compound represented by the following general formula (I). An electrophotographic photoreceptor characterized by containing. General formula (I) (However, in the general formula (I), Ar ₁ and Ar ₂ may each be substituted with an alkyl group, a phenyl group, an alkoxy group or a phenyl group which may be substituted with an alkyl-substituted phenyl group, or an alkyl group. Good polycyclic aromatic groups,
Or, it represents an aromatic heterocyclic group. ) 2. The electrophotographic photosensitive member according to claim 1, wherein the charge generation layer contains a phthalocyanine compound represented by the following general formula (II) as a charge generation substance. General formula (II) (However, in the general formula (II), M represents Cu, Fe, Mg, Si, Ge, Sn, Pb, I
n, Ga, Al, Ti containing form, or 2 hydrogen atoms
Represents the added form. X represents a hydrogen atom, an alkyl group, an alkoxy group, an alkoxyalkyl group, a nitro group, a cyano group, or a halogen atom. m represents an integer of 0 to 4. ) 3. A contact charging type electrophotographic apparatus, comprising:
An electrophotographic apparatus comprising the electrophotographic photosensitive member according to claim 1. 4. An electrophotographic apparatus of a reversal developing system,
An electrophotographic apparatus comprising the electrophotographic photosensitive member according to claim 1.